1. Field of the Invention
The present invention relates to a keypad apparatus for a portable communication device. More particularly, the present invention relates to a keypad apparatus for a portable communication device in which a plurality of pressurizing protrusions are integrated with a plurality of dome switches instead of with a keypad.
2. Description of the Related Art
Generally, the term “portable communication device” denotes a device by which wireless communication can be performed while the device is being carried. Examples of a portable communication device include a Hand Held Phone (HHP), a Cordless Telephone (CT-)2 cellular phone, a digital phone, a Personal Communications Systems (PCS) phone, and a Personal Digital Assistant (PDA), which are sorted into various types according to their shapes. For example, the wireless terminals are sorted into a bar type, a flip type, a folder type, and a sliding type according to their shapes. The above-mentioned portable terminals always include an antenna apparatus, a data input/output device, and a data transceiver. For the data input device, a keypad assembly allowing data input through a finger press is generally used; for the data output device, a display device is used.
FIG. 1 is a front view showing a keypad apparatus for a portable communication device according to the prior art. FIG. 2 is a side cross-sectional view showing a structure of a keypad apparatus for a portable communication device according to the prior art.
Referring to FIGS. 1 and 2, a keypad assembly 1 includes a keypad 2 including a plurality of key buttons 2a, a board 3, formed under the keypad 2 and including a plurality of dome switches 3a for inputting a signal by pressing of the key buttons 2a and a plurality of light-emitting devices (not shown), and a light path (or waveguide) 4 disposed between the keypad 2 and the board 3 to uniformly diffuse light emitted from the light emitting devices.
As shown in FIGS. 1 and 2, on a bottom surface of the keypad 2 are formed a plurality of pressurizing protrusions 2b for pressing and pressurizing the plurality of dome switches 3a, respectively, and between the key buttons 2a is configured a front frame 5.
The keypad 2 is made of a silicon material and a thickness of the keypad 2 needs to be more than 0.9 mm due to characteristics of silicon and formation of the pressurizing protrusions 2b. 
However, in the keypad assembly 1, when the keypad 2 having a thickness of less than 0.9 mm is pressed, pressing of the pressurizing protrusions 2b of the keypad 2 deviates from the corresponding dome switches 3a due to the characteristics of silicon, making accurate signal input difficult. For this reason, the thickness of the keypad assembly 1 needs to be more than 0.9 mm, thus increasing the overall thickness of the product.
Moreover, a user, when pressing the keypad 2, may also feel the pressurizing protrusion 2b, such that a sense of clicking of the product is degraded.
The front frame 5 of the prior art is made of Poly-Carbonate (PC) or PC+Glass Fiber (GF).
The minimum thickness of the front frame 5 made of the foregoing material needs to be more than 0.6 mm. Otherwise, insufficient filling or shrinking may occur.
As such, the thickness of the keypad 2 has to be more than 0.9 mm and the thickness of the front frame 5 has to be more than 0.6 mm, both of which contribute to an increased thickness of the product.
Therefore, to reduce the size of a product by reducing the thickness of the keypad 2 and the thickness of the front frame 5, the pressurizing protrusions 2b need to be integrated with the plurality of dome switches 3a, instead of with the keypad 2, and a material capable of reducing the thickness of the front frame 5 to 0.6 mm or less needs to be used.